Effects of an energy-restricted low-carbohydrate, high unsaturated fat/low saturated fat diet versus a high-carbohydrate, low-fat diet in type 2 diabetes: A 2-year randomized clinical trial.
Study Goal
The researchers aimed to compare the effects of a low-fat, high-carbohydrate diet (HC) versus a low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) on glycemic control and cardiovascular disease risk factors in overweight/obese patients with type 2 diabetes.
Results Summary
Both diets achieved similar weight loss and HbA1c reductions, but the LC diet showed greater improvements in diabetes medication reduction, glycemic variability, and blood lipid profile without adverse renal effects. The HC diet performed comparably in weight loss and HbA1c but was less effective in these secondary outcomes.
Population
Overweight and obese adults with type 2 diabetes (mean BMI 34.6 kg/m², age 58 years).
Effective Dosage
HC diet: 53% carbohydrate, 17% protein, 30% fat (<10% saturated fat), energy-matched and hypocaloric.
Duration
2 years
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | weight | overweight and obese patients with type 2 diabetes (T2D) | -6.8 [-8.8,-4.7] kg | reductions in weight | #1 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | weight | overweight and obese patients with type 2 diabetes (T2D) | -6.6 [-8.8, -4.5] kg | reductions in weight | #2 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | body fat | overweight and obese patients with type 2 diabetes (T2D) | -4.3 [-6.2, -2.4] kg | reductions in body fat | #3 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | body fat | overweight and obese patients with type 2 diabetes (T2D) | -4.6 [-6.6, -2.7] kg | reductions in body fat | #4 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | blood pressure | overweight and obese patients with type 2 diabetes (T2D) | -2.0 [-5.9, 1.8]/ -1.2 [-3.6, 1.2] mmHg | reductions in blood pressure | #5 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | blood pressure | overweight and obese patients with type 2 diabetes (T2D) | -3.2 [-7.3, 0.9]/ -2.0 [-4.5, 0.5] mmHg | reductions in blood pressure | #6 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | HbA1c | overweight and obese patients with type 2 diabetes (T2D) | -0.6 [-0.9, -0.3] % | reductions in HbA1c | #7 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | HbA1c | overweight and obese patients with type 2 diabetes (T2D) | -0.9 [-1.2, -0.5] % | reductions in HbA1c | #8 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | fasting glucose | overweight and obese patients with type 2 diabetes (T2D) | 0.3 [-0.4, 1.0] mmol/L | reductions in fasting glucose | #9 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | fasting glucose | overweight and obese patients with type 2 diabetes (T2D) | -0.4 [-1.1, 0.4] mmol/L | reductions in fasting glucose | #10 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | anti-glycaemic medication effect score (MES) | overweight and obese patients with type 2 diabetes (T2D) | -0.5 [-0.6, -0.3] units | greater reductions in diabetes medication use | #11 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | anti-glycaemic medication effect score (MES) | overweight and obese patients with type 2 diabetes (T2D) | -0.2 [-0.4, -0.02] units | reductions in diabetes medication use | #12 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | Continuous Overall Net Glycemic Action calculated every 1 hour | overweight and obese patients with type 2 diabetes (T2D) | -0.4 [-0.6, -0.3] mmol/L | greater reductions in glycaemic variability | #13 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | Continuous Overall Net Glycemic Action calculated every 1 hour | overweight and obese patients with type 2 diabetes (T2D) | -0.1 [-0.1, 0.2] mmol/L | reductions in glycaemic variability | #14 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | Continuous Overall Net Glycemic Action calculated every 4 hours | overweight and obese patients with type 2 diabetes (T2D) | -0.9 [-1.3, -0.6] mmol/L | greater reductions in glycaemic variability | #15 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | Continuous Overall Net Glycemic Action calculated every 4 hours | overweight and obese patients with type 2 diabetes (T2D) | -0.2 [-0.6, 0.1] mmol/L | reductions in glycaemic variability | #16 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | triglycerides | overweight and obese patients with type 2 diabetes (T2D) | -0.1 [-0.3, 0.2] mmol/L | greater reductions in triglycerides | #17 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | increase | triglycerides | overweight and obese patients with type 2 diabetes (T2D) | 0.1 [-0.2, 0.3] mmol/L | changes in triglycerides | #18 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | no change | HDL-C levels | overweight and obese patients with type 2 diabetes (T2D) | 0.02 [-0.05, 0.1] mmol/L | maintained HDL-C levels | #19 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | HDL-C levels | overweight and obese patients with type 2 diabetes (T2D) | -0.1 [-0.1, 0.01] mmol/L | changes in HDL-C levels | #20 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | increase | LDL-C | overweight and obese patients with type 2 diabetes (T2D) | 0.2 [-0.1, 0.5] mmol/L | similar changes in LDL-C | #21 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | increase | LDL-C | overweight and obese patients with type 2 diabetes (T2D) | 0.1 [-0.2, 0.4] mmol/L | similar changes in LDL-C | #22 |
low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) combined with aerobic/resistance exercise | decrease | brachial artery flow mediated dilatation | overweight and obese patients with type 2 diabetes (T2D) | -0.5 [-1.5, 0.5] % | similar changes in brachial artery flow mediated dilatation | #23 |
low-fat, high-carbohydrate, low-glycaemic index diet (HC) combined with aerobic/resistance exercise | decrease | brachial artery flow mediated dilatation | overweight and obese patients with type 2 diabetes (T2D) | -0.4 [-1.4, 0.7] % | similar changes in brachial artery flow mediated dilatation | #24 |
AIM: To examine whether a low-carbohydrate, high-unsaturated/low-saturated fat diet (LC) improves glycaemic control and cardiovascular disease (CVD) risk factors in overweight and obese patients with type 2 diabetes (T2D). METHODS: A total of 115 adults with T2D (mean [SD]; BMI, 34.6 [4.3] kg/m2 ; age, 58 [7] years; HbA1c, 7.3 [1.1]%) were randomized to 1 of 2 planned energy-matched, hypocaloric diets combined with aerobic/resistance exercise (1 hour, 3 days/week) for 2 years: LC: 14% energy as carbohydrate, 28% as protein, 58% as fat (<10% saturated fat); or low-fat, high-carbohydrate, low-glycaemic index diet (HC): 53% as CHO, 17% as protein, 30% as fat (<10% saturated fat). HbA1c, glycaemic variability (GV), anti-glycaemic medication effect score (MES, calculated based on the potency and dosage of diabetes medication), weight, body composition, CVD and renal risk markers were assessed before and after intervention. RESULTS: A total of 61 (LC = 33, HC = 28) participants completed the study (trial registration: http://www.anzctr.org.au/, ANZCTR No. ACTRN12612000369820). Reductions in weight (estimated marginal mean [95% CI]; LC, -6.8 [-8.8,-4.7], HC, -6.6 [-8.8, -4.5] kg), body fat (LC, -4.3 [-6.2, -2.4], HC, -4.6 [-6.6, -2.7] kg), blood pressure (LC, -2.0 [-5.9, 1.8]/ -1.2 [-3.6, 1.2], HC, -3.2 [-7.3, 0.9]/ -2.0 [-4.5, 0.5] mmHg), HbA1c (LC, -0.6 [-0.9, -0.3], HC, -0.9 [-1.2, -0.5] %) and fasting glucose (LC, 0.3 [-0.4, 1.0], HC, -0.4 [-1.1, 0.4] mmol/L) were similar between groups (P ≥ 0.09). Compared to HC, the LC achieved greater reductions in diabetes medication use (MES; LC, -0.5 [-0.6, -0.3], HC, -0.2 [-0.4, -0.02] units; P = 0.03), GV (Continuous Overall Net Glycemic Action calculated every 1 hour (LC, -0.4 [-0.6, -0.3], HC, -0.1 [-0.1, 0.2] mmol/L; P = 0.001), and 4 hours (LC, -0.9 [-1.3, -0.6], HC, -0.2 [-0.6, 0.1] mmol/L; P = 0.02)); triglycerides (LC, -0.1 [-0.3, 0.2], HC, 0.1 [-0.2, 0.3] mmol/L; P = 0.001), and maintained HDL-C levels (LC, 0.02 [-0.05, 0.1], HC, -0.1 [-0.1, 0.01] mmol/L; P = 0.004), but had similar changes in LDL-C (LC, 0.2 [-0.1, 0.5], HC, 0.1 [-0.2, 0.4] mmol/L; P = 0.85), brachial artery flow mediated dilatation (LC, -0.5 [-1.5, 0.5], HC, -0.4 [-1.4, 0.7] %; P = 0.73), eGFR and albuminuria. CONCLUSIONS: Both diets achieved comparable weight loss and HbA1c reductions. The LC sustained greater reductions in diabetes medication requirements, and in improvements in diurnal blood glucose stability and blood lipid profile, with no adverse renal effects, suggesting greater optimization of T2D management.